Assessment of watercourses in terms of their impact on flood hazards: a case study from a mountain river basin

The aim of this case study is to present a methodological approach for the flood hazard assessment of small watercourses, based on the evaluation of the impact of the morphology of the watercourse channel, land cover of the floodplain, transport infrastructures along the watercourse, bank and channel vegetation, negative attributes of vegetation, and debris in the channel. Each variable is represented by a set of attributes that characterise the current state of the watercourse reach. The assessment process begins with the division of watercourses into river reaches based on a mutual combination of variables influencing the flood hazard. Subsequently, the current state of the variable attributes of each river reach is identified and their impact on flood hazards is then assessed according to rational rules. The impact of the individual attributes is first expressed on an ordinal scale, which is then transformed into a quantitative weight. The overall Flood Hazard Index (FHI) of the river reach is then determined through the aggregation of the quantitative weights of the impact of individual attributes. Key words: Flood hazard index, watercourse attributes, municipality, riverine landscape, river reach